The present invention relates to a reference voltage generator integrated on a semiconductor integrated circuit.
A large number of portable equipments using LSI as represented by a notebook type personal computer have been produced in recent years. In such portable equipments, the discharging time of a battery has become important. It is therefore important to reduce the power dissipation of LSI used in portable equipments. Recently, DRAMs have been used in such portable equipments as a storage device substituting for a floppy disk or a hard disk, and power reduction of DRAMs is required. Particularly in DRAM, power reduction of a reference voltage generator and a substrate bias voltage circuit is important because they consume power constantly.
A circuit disclosed in JP-A 1-296491 is an example of the reference voltage generator. This circuit generates a reference voltage in accordance with the threshold voltage difference between the MOS-FETs. In this circuit, the value of the reference voltage changes in accordance with variation of threshold voltage, but the influence thereof decreases as the operation current increases. Further, as the operation current increases, the influence of noise from a substrate decreases.